Section 3. The commissioner of conservation and recreation shall be the executive and administrative officer of the department, and he shall exercise supervision, direction and control over all the divisions of the department in accordance with such programs and policies as may from time to time be promulgated by the stewardship council. The commissioner shall be responsible for administering all laws vested in the department by general or special laws. The commissioner shall appoint and remove the directors of state parks and recreation and water supply protection with the approval of the stewardship council. The commissioner shall appoint and remove the directors of other divisions, bureaus or offices which he may establish as he deems appropriate for the efficient management and centralized administration of the department. The directors shall be qualified by training, executive ability, relevant experience and personal participation in the public programs of federal, urban, or state parks and recreation systems, to administer the duties of their respective offices, and shall not be subject to chapter 31. The commissioner may also appoint and remove a professional geologist, who shall be the state geologist and who shall not be subject to chapter 31 or section 9A of chapter 30.